Railway skate car retarder

ABSTRACT

This invention relates to a weight proportional skate car retarder including a plurality of levers pivotally supported on the cross ties and disposed on the respective sides of a track rail. The pivotal levers carry elongated braking elements which are disposed parallel to the track rails and are operable to apply brake pressure to both sides of the rims of the car wheels. Each of the outer levers of the car retarder is normally biased and held in an upper braking position. Each outer lever is rigidly held in its upper braking position by a movable support having an electromechanical locking apparatus which includes a motor operated latching unit. The release of the latching unit allows the movable support to move which causes the outer levers to collapse under the weight of a car, and thereby causes the braking elements to move the car retarder to its lower nonbraking position.

United States Patent Noble RAILWAY SKATE CAR RETARDER Peter M. Noble, Valencia, Pa.

[73] Assignee: Westinghouse Air Brake Company,

Swissvale, Pa.

22 Filed: Jan. 2, 1973 21 Appl, No.: 320,311

[75] Inventor:

[52] U.S.Cl. 188/62 [51] Int. Cl B6lk 7/06 [58] Field of Search 188/32, 62

[5 6] References Cited UNITED STATES PATENTS 3,209,865 10/1965 Wynn 188/62 Primary Examiner-Duane A. Reger Attorney, Agent, or FirmH. A. Williamson; J. B. Sotak May 28, 1974 [57} ABSTRACT I This invention relates to a weight proportional skate car retarder including a plurality of levers pivotally supported on the cross ties and disposed on the respective sides of a track rail. The pivotal levers carry elongated braking elements which are disposed parallel to the track rails and are operable to apply brake pressure to both sides of the rims of the car wheels. Each of the outer levers of the car retarder is normally .biased and held in an upper braking position. Each outer lever is rigidly held in its upper braking position by a movable support having an electromechanical locking apparatus which-includes a motor operated latching unit. The release of the latching unit allows the movable support to move which causes the outer levers to collapse under the weight of a car, and thereby causes the braking elements to move the car retarder to its lower nonbraking position.

10 Claims, 4 l)rawing Figures i RAILWAY SKATE CAR RETARDER This invention relates to a railway weight proportional skate car retarder which is operably controlled to cause either a braking or a nonbraking action. More particularly, this invention involves an electromechanical locking apparatus for controlling the condition of a car wheel frictional engaging type of railroad braking apparatus.

It is conventional practice to employ skates or chocks at the exiting ends of the railway class tracks in classification yards and also at certain points in industrial and commercial sidings or spur tracks to brake and stop oncoming railway vehicles, and subsequently to hold them in place. The skate or chock is generally manually placed on one or both of the rails of the trackway so that the treadles or rims of the wheel or wheels will cause frictional retardation and will result in the halting of the railwayvehicle; In order to alleviate the shortcoming, such as, the manual placement and removal of the skates or chocks by a brakeman or other personnel, it is preferable to employ vehicle stopping apparatus which require little, if any, handling by attending workmen. lt is now becoming common railroad practice to utilize spring type or weight proportional inert car retarders in place of the previously used skates or chocks. However, the railroad industry is now faced with the problem of noise pollution, such as, the wheel screechin g sounds that are generated when the railway vehicles are pulled from the bowl class tracks through the skate retarder by a departure yard locomotive or engine. ln view of the recently enacted noise abatement ordinances by 'many of the cities, towns, and other municiple governments, it is mandatory to suppress or at least decrease the level of the squealing sounds that are produced by frictional wheel engaging car retarders. In addition, the passage of the Occupational Safety and Health Act requires the employer assure as far as possible every working man and woman in the nation safe and healthful working conditions and to preserve our human resources." The scope of the Act encompasses noise pollution, and thus the wheel squealing noise produced in a frictional type of skate car retarder must be dramatically reduced and preferably eliminated, particularly, during withdrawal or pullout periods. The wheel squealing noise is produced by the brake shoes frictionally rubbing the sides of the moving car wheels which results in severe vibrational agitation that results in extremely loud and intense soundsto be created during a pullout operation. Thus, it is necessary to maintain the retaining or braking function of the skate retarder during classification operation, but it is essential to avoid generating wheel squealing or screeching during pullout operation. As mentioned above, the noise problem is caused by the rubbing 'action that takes place between the wheels and brake shoes. Hence, the wheel squealing sounds may be completely eliminated by precluding any braking effort from occurring when eliminated by precluding any braking effort from occurring when railway vehicles are pulled through the weight proportional skate car retarder by a departure engine. In addition, the frictional rubbing action causes excessive mechanical wear on the brake shoes orbraking rails which drastically reduces the useful life of thebraking elements. It has been found that the useful life of the braking elements is dramatically reduced due to the excessive abrasive wear that previously occurred during pullout operation. This was wholly unacceptable in that the cost of adjusting and replacing the braking elements becomes exorbitant. Thus, the short life of the braking elements greatly increases the cost, and the accelerated abrasion also demands frequency adjustments of the braking elements for maintaining effective and efficient retarder operation. Hence, it is desirable to normally maintain the skate car retarder in its braking position during classification of the railway vehicles and to periodically move the skate car retarder to its nonbraking position during withdrawal of the railway vehicles. Further, the power required or the load demanded of the departure yard locomotive is greatly diminished by the elimination of the frictional drag on the car wheels during pullout operations.

Accordingly, it is an object of this invention to provide a weight proportional car retarder for effectively braking the wheels, stopping free rolling railway cars, and for holding the wheels, and for selectively allowing the free passage of the wheels of the moving railway cars.

A further'object of this invention is to provide a controllable skate car retarder which is capable of assuming a braking or a nonbraking position.

Another'object of this invention is to provide a vertically movable support assembly for a weight proportional skate car retarder which brakes the wheels of railway vehicles during classification operation and which allows the free passage of the wheels of the railway vehicles during pullout operation.

Still anotherobject of this invention is to provide a plurality of controllable pivotal support assemblies for a skate type of car tender so that little, if any, wheel squeal will be produced when railway cars are withdrawn by an engine.

Still a further object of this invention is to provide a railway weight proportional car retarder which is locked in a first position to frictionally engage the sides of the wheels for stopping railway cars and which is arranged to assume a second position by the weight of cars so that wheel screeching sounds will not be generated when the railway cars are pulled out of the retarder.

Yet another object of this invention is to provide an operable weight proportional skate car retarder having a pluralityof operating units which are normally biased to and latched in a braking position for stopping oncoming railway cars and which are unlatched and moved to a nonbraking position for allowing free withdrawal of the railway cars so that noise pollution is effectively avoided and frictional wear is markedly reduced.

Yet a further object of this invention is to provide a unique releasable skate type of railway car retarder which is economical in cost, simple in construction. easy to install, reliable in operation, durable in use, and efficient in service.

Briefly, the objects of this invention are achieved by providing vertically movable support assemblies for a skate type of weight proportional car retarder having a plurality of operating units including a pair of pivotal levers and frictional braking elements mounted on opposite sides of the track rail. Each of the vertically movable support assemblies includes a power operated locking mechanism and aspring biased slide cylinder and piston members. The power ope-rated locking mechanism includes an electric motor, a worm gear, and a sector gear for controlling the angular disposition of a splined sleeve member in relation to the projecting teeth located on the slide cylinder member. One end of the slide cylinder is pivotally connected to a journal pin which is fixedly attached to the underside of the outer extremity of one of the pair of the pivotal levers. The one end of the piston member is firmly mounted to a base plate which is securely fastened to the top of the cross tie. The other end of the piston member accommodates the extendable slide cylinder which is capable of moving longitudinally between a retracted and an extended position. A helical compression spring is disposed internally of the tubular piston and cylinder members and constantly urges the cylinder to its extended position. The lower peripheral surface of the slide cylinder is provided with a number of outwardly projecting splines or teeth. To accomplish retardation of the car wheels by the frictional braking elements, the cylinder member is locked or latched in its extended position by having the inwardly projecting teeth of the splined sleeve member engaging the outwardly projecting teeth of the cylinder member. However, during pullout operation, the electric motor drives the worm gear and, in turn, the sector gear, which rotationally moves the teeth out of alignment with each other. Thus, the car weight is permitted to compress the biased cylinder member to its retracted position so that the braking elements move apart which causes the retarder to assume its open nonbraking position. Accordingly, little, if any, drag occurs so that noise pollution is abated and excessive frictional wear on the braking elements is avoided.

The above objects and other attendant features and advantages ofthis invention will become more fully evident from the following detailed description when considered in connection with the accompanying drawings, wherein: I

FIG. 1 is a top plan view ofa skate type of weight proportional car retarder of the present invention showing the two end operating units and two intermediate operating units with the other intermediate operating units being broken away for the purpose of convenience.

FIG. 2 is an enlarged fragmentary side elevational view of the car retarder embodying the present invention.

FIG. 3 is a greatly enlarged partial sectional view of one of the movable support assemblies of one of the operating units of the skate type of weight proportional car retarder constructed in accordance with the present invention.

FIG. 4 is a partial horizontal sectional view taken along the lines IVIV of FIG. 3.

Similar reference characters will refer to analogous parts throughout the several views of the drawings.

Referring now to the drawings, and in particular to FIG. I, the reference characters R1 and R2 designate the rails of a stretch of railway track over which the wheels of railway cars traverse and enter the braking apparatus embodying the invention. It will be understood that the rails R1 and R2 are suitably connected to the respective ends of the class or stock rails 51 and S2 in the usual manner by means of rail joints. It will be appreciated that the fasteners or spikes for securing the stock rails allow sufficient vertical lift of the rails for a suitable distance outside the ends of the retarder to permit the running rail in the retarder to lift a given amount. In practice, a conventional 33 ft. retarder will have a vertical movement of approximately one-half of an inch at 6 ft. outside the end of the retarder. It will be understood that the fastening of the rails R1 and R2 to the stock rails at the other end is effected in a corresponding manner. As shown, the stock rails S1 and S2, as well as the rails R1 and R2, rest upon the wooden cross ties CT which are suitably anchored in a conventional manner, such as, being set in ballast in the ground.

As shown, the rail R1 of the braking apparatus or weight proportional car retarder is preferably supported and carried by a plurality of suitably spaced operating units 0U, each of which consists of a pair of substantially identical pivotal levers 2a and 2b, of the generally known type, disposed laterally on opposite sides of the rail R1. in viewing FIG. 2, it will be noted that the pivotal levers 2a and 2b are weldments, each being an assembly of pieces that are welded together. As shown, the two levers 2a and 2b have their inside bottom portions securely held in suitable relationship by means of a through tie bolt 3. In addition, in viewing FIG. 2, it will be noted that the upper surface of the inside bottom portions of each of the levers 2a and 2b carries the flange or base portion of the rail R1. The lower surfaces of the inside bottom portions of each of the levers 2a and 2b include a contact rod or bar 40 and 412, respectively. The contact rods 40 and 4b normally rest upon the upper surface of a horizontal bearing plate 5a of a suitable cradle 6. The cradle 6 includes two vertical slide supporting plates 5b and 50 which are secured, such as, being welded to the upper surface of a bearing support plate 7. The bearing plate 7 rests on the top and is suitably secured, such as being bolted, to the wooden cross tie CT. In order to provide a more stable supporting arrangement the bearing plate 7 is prefabricated and welded to a pair of oppositely disposed angle irons, one of which is characterized by the numeral 8. The angle irons are secured to the cross ties CT by through tie bolts ,9. As shown, the upper inner end of each of the levers 2a and 2b of the operating units supports the braking elements which may consist of conventional braking rails, or, as shown, brake beams 10a and 10b and removable brake shoes 11a and 11b. In viewing FIG. 2, itwill be noted that the brake shoes 11a and 1122 are adapted to frictionally engage the opposite sides of a car wheel 13 when the weight porportional car retarder is in its closed braking positron.

For the sake of convenience, let us assume that the presently described weight proportional car retarder is located at the exit end of a class track in a multi-track railroad marshalling or classification yard. In such an environment the car retarder is normally set in its closed braking position, in order to retard, stop, and hold the oncoming cars by frictionally engaging the opposite sides of wheels of the cars, as shown in FIG. 2. Normally, the first railway car or vehicle of a string of cars is stopped by the car retarder to prevent the remaining oncoming vehicles from exiting the class track until such time as it is desirable to withdraw or pull out the string of cars for a train makeup in the departure yard. When the cars in the class track are ready for makeup, a departure yard locomotive or engine enters the class track and couples to the first car and pulls the string of cars from the class track. it has been found that the pulling of the cars through a closed skate type of weight proportional car retarder results in severe wheel squealing noises and excessive mechanical wear due to the frictional rubbing action occurring between the brake shoes 11a and 11b and the sides of the wheel 13. The noise emanating from the retarder not only is annoying but also is harmful to attending personnel since car retarder noise levels have been measured well in excess of 130 db (decibels) which is well in excess of the threshold of pain level. In addition, in some yard installations the wheel squealing sounds are in violation of the noise abatement ordinances of the community. Thus, in order to comply with local, state, and federal law, it is necessary to reduce and preferably to eliminate the wheel squeal caused by the frictional rubbing action that occurs during pullout or withdrawal operatrons.

Thus, in order to eliminate the noise problem as well as to reduce the mechanical wear on the brake shoes 11a and 11b, it is advisable to allow the retarder to assume an open or nonbraking position during pullout. The opening of the braking elements or brake shoes during pullout results in an additional benefit in that less power is required by the locomotive to withdraw the cars from the track. As shown in FIG. 1, the outside end of the inner lever 2b is pivotally mounted on a suitable fixed support member or stand 9. The stand 9 positions the lever 2b at approximately the same height as that of the outer levers 2a when both of the levers are in their closed braking position. The predetermined fixed heights are determined by the average width of the traversing car wheels to ensure that maximum braking efforts are exerted on the wheels as they enter the weight proportional car retarder. As shown in FIG. 1, each of the operating units OU includes a movable support assembly or variable pivotal stand MSA. It will be appreciated that each of the variable support assemblies MSA is similar and substantially identical in construction and, therefore, the details of only one of the assemblies MSA need be described to fully understand the structural features and the functional operation thereof. Each of the movable support stands MSA includes a power operated locking arrangement and a spring biased slide cylinder and piston members and 21, respectively.

The power operated locking means includes a reversible electric motor M. As shown in FIG. 1, the motor of each of the power operators is connected to conductors or leads L1 and L2 of a suitable source of supply voltage 24, such as a conventional l lOV, 60 Hz. power source. It will be appreciated that each of the motors M drives a worm gear W which engages the teeth of sector gear G. The worm gear W is positioned on the output shaft S of the electric motor M. The free end of the shaft S is journaled in the bearing block B which minimizes the adverse effects of shock and vibration on the gear drive by stabilizing the structural configuration. The journal block B is securely mounted to the top ofa base plate 23. The base plate 23 is securely fastened to the top ofa cross tie CT by means of lag bolts 24 or the like. The flat base plate 23 provides an appropriate support for the remaining parts or elements of the support assembly MSA which may be put together at a subassembly location. It will be appreciated that the base plate 23 facilitates the positioning and assembling of the various parts or elements of the support stand MSA. The lower end of the fixed piston member 21 is also secured, such as, being welded, to the top or upper surface of the base plate 23. The upstanding tubular piston 21 accommodates the exterior tubular cylinder 20. An end plate or disk 25 is attached to the upper extremity or top of the tubular cylinder member trunnion 26 receives a pivot pin or rod 27. The pivotpin 27 is secured, such as being welded, to the underside of the outer extremity of the outer pivotal lever 20. Thus, the outer lever is pivotally connected to the movable support assembly MSA which is arranged to have the car retarder assume a braking or nonbraking position, as will be described in detail hereinafter.

As shown, a helical compression spring 30 is situated or disposed internally of the tubular or hollow piston 21 and cylinder 20. A cylindrical spring retainer 31 is secured to the base plate 23. Thus, the one end of the coil spring 30 is circumposed about the retaining ring 31 and abuts the upper surface of bearing plate 23. The other end of the compression spring 30 abuts the underside of the end plate 25-which includes a retaining ring 32 which holds the upper end of spring 30 in place against the underside of the end plate 25. Since the coil spring 30 is under compression, a continual force is exerted upon slide cylinder 20 so that the cylinder is constantly urged or biased upwardly or vertically to its uppermost position. The displacement of the slide cylinder 20 is limited by the four stop pins 33 which are carried by the cylinder 20 and cooperate with the elongated slots 34 formed in the peripheral surface of the fixed piston 21. As shown, the pins 33 engage the lower extremities of the slots 34 when the slide cylinder is fully extended by the compression spring 30. The pins 33 also prohibit rotational movement to occur between the cylinder and piston in that the pins follow the linear or straight side walls of the slots 34. Thus, the pins 33 operate as a stopping as well as a guiding means. As shown, the lower peripheral portion of the slide cylinder 20 includes a number of outwardly extending splines or external projecting teeth 36. In the present case, there is shown four projecting splines 36 situated at intervals and having a mean arcuate length of slightly less than 45. However, it is understood that a lesser or greater number of teeth may be located on the lower peripheral surface of cylinder member 20. The teeth 36 interact and cooperate with the teeth of a splined sleeve member 38 which encompasses the cylinder member 20. The sleeve member 38 includes a plurality of inwardly extending splines or internal projecting teeth 39. Like teeth 36, there are four equally spaced teeth 39, each of which is slightly less than 45 in mean arcuate length. The arcuate teeth 36 and 39 form a locking device or means whereby the movable support assembly is latched in its upper position, as shown in the drawings. That is, the cylinder 20 is locked in its upper extended position due to the engagement of the underside of teeth 36 with the upper side of teeth 39. Thus, the lever 2a is rigidly held in its upper position, the brake shoes are closed, and the car retarder is in its braking position to frictionally engage opposite sides of the wheels 13, as shown in FIG. 2. In the present instance it will be noted'that gear teeth form a sector gear G 'on the peripheral edge of the sleeve member 38. Thus, the sleeve member 38 moves in accordance with the rotational displacement of the gear teeth G which cooperate with the treadle of the rated upon -the upper surface of a cylindrical thrust bearing block 40. A snap ring 41 is held in an annular slot or recess formed in the inner cylindrical wall of an outer protective shell member 42. The lower rim of block 40, as well as shell 42, is securely fastened, such as being welded, to the upper surface of bearing plate 23. A metallic case or cover member 45 is carried by the slide cylinder 20 and protects the entire support assembly against the adverse effects of the surrounding environment.

In a classification yard environment, the car retarder is generally held in its illustrated braking position until such time as it is desired to withdraw the railway vehicles from a particular class track. If it is desired to pull the string of vehicles from the class track, it is necessary to open and spread apart the braking elements, namely, the brake shoes 11a and 11b. Operationally, this permits the weight of the vehicles to move the retarder to its open nonbraking position. However, in order to move the car retarder to its open nonbraking position, it is initially required to unlock or unlatch each of the operating units OU. The retarder is unlatched by electrically energizing the motors M from voltage source 24 over lines L1 and L2. The energization of each of the motors causes the worm gear W to rotate and cause its associated sector gear G to become angularly displaced approximately 45. The angular displacement results in the movement of the splines or teeth 39 of the sleeve member 38 relative to the splines or teeth 36 of the slide cylinder 20. The disengagement of the teeth 39 and 36 allows the weight of the cars to depress spring 30 and to contract the movable support MSA. The contraction results in the opening of the braking elements, namely, beams lla and lib, so that little, if any, frictional drag is applied to the sides of the wheels of the railway vehicle. Thus, the fulcrum point of the levers 2a are lowered to a point where the gap between the brake shoes Ila and 1 lb becomes substantially equal to the width of the car wheels 13 so little, if any, rubbing action takes place. Thus, free passage of the vehicles is permitted without generation of wheel squeal and without mechanical frictional wear on the wheel engaging surfaces of the brake shoes. After the last car has been withdrawn, the car retarder is automatically allowed to move to its upper braking position. That is, the compression of the compression spring 30 is sufficient to overcome the dead weight of the car retarder. Once the springs 30 raise the levers 2a to their upper pivotal braking position, the motors M are energized so that the worm gear W turns the sector gear G and causes the lower teeth 39 to again overlap and engage upper teeth 36. The engagement of the two sets of teeth locks and latches the slide cylinder 20 in place, and the braking elements are in their closed position. Thus, the car retarder is automatically returned to its braking position so that the forthcoming vehicle of the next string of cars to be classed is held until pullout time.

in practice, the position of the car retarder is normally controlled by an operator located in the central control tower of the classification yard. As previously mentioned, once the levers 2a are moved to their raised position, it is only necessary to momentarily energize motors M from the voltage supply source 24 so that the amount of power consumed is minimized.

From the foregoing description it will be noted that the presently described invention utilizes a simple, yet efficient, arrangement for controlling a weight proportional skate car retarder which provides sufficient braking effort to stop oncoming vehicles and yet selectively allows the free passage of railway cars through the retarder. during withdrawal or pullout operation.

While the subject skate retarder equipment has been described in relation to classification yards, it is readily understood that the present invention may be employed in other applications, such as, car dumping, industrial sidings, as well as in other environmental surroundings having need of my invention. But regardless of the manner in which the invention is used, it is understood that various alterations may be made by persons skilled in the art without departing from the spirit and scope of this invention. It will also be apparent that any modifications and changes can be made in the presently described invention and, therefore, it is understood that all changes, equivalents, and modifications within the spirit and scope of this invention are herein meant to be included in the appended claims.

Having thus described my invention, what I claim is:

1. A railway skate car retarder comprising, a plurality of operating units disposed along the length of at least one rail of a section of the trackway, each of said operating units including a pair of levers each of which is situated on the respective sides of at least said one rail and pivotally mounted to the cross ties, an elongated braking means carried by the respective one of said pair of pivotal levers and adapted to be moved between a closed braking position and an open nonbraking position, at least one of said pair of levers of said operating units including a movable support assembly having a biasing means for normally urging said braking means to said closed braking position, and a power gear operated locking means for latching said movable support and for holding said braking means in said closed braking position and for unlatching said movable support and for allowing said braking means to move to said open nonbraking position.

2. A railway skate car retarder as defined in claim 1, wherein said movable support includes a longitudinally movable and rotationally immovable slide cylinder and piston which are carried by the cross ties.

3. A railway skate car retarder as defined in claim 1, wherein said biasing means is a helical compression spring which extends said movable support and moves said brake means to said braking position.

4. A railway skate car retarder as defined in claim 1, wherein said power gear operated locking means includes an electric motor and a worm and gear for latching and unlatching a pair of splined fittings.

5. A railway skate car retarder as defined in claim 3,

wherein said helical compression spring is internally located in a tubular piston and slide cylinder member.

6. A railway skate car retarder as defined in claim 1, wherein said power gear operated locking means includes a motor and gears for operating a spline type of latching device.

7. A railway skate car retarder as defined in claim 1, wherein said movable support includes a pair of telescoping members which are urged outwardly by said biasing means.

9 l4) 8.'A railway skate car retarder as defined in claim 2, v 10. A railway skate car retarder as defined in claim wherein said slide cylinder is constantly urged to an ex- 2, wherein said cylinder includes a plurality of outtended position by said biasing means. wardly extending splines which engage a plurality of in- 9. A railway skate car retarder as defined in claim 8, wardly extending splines when the car retarder is wherein said biasing means is a helical spring which is 5 latched in its closed braking position. located internally of said piston and said cylinder. 

1. A railway skate car retarder comprising, a plurality of operating units disposed along the length of at least one rail of a section of the trackway, each of said operating units including a pair of levers each of which is situated on the respective sides of at least said one rail and pivotally mounted to the cross ties, an elongated braking means carried by the respective one of said pair of pivotal levers and adapted to be moved between a closed braking posiTion and an open nonbraking position, at least one of said pair of levers of said operating units including a movable support assembly having a biasing means for normally urging said braking means to said closed braking position, and a power gear operated locking means for latching said movable support and for holding said braking means in said closed braking position and for unlatching said movable support and for allowing said braking means to move to said open nonbraking position.
 2. A railway skate car retarder as defined in claim 1, wherein said movable support includes a longitudinally movable and rotationally immovable slide cylinder and piston which are carried by the cross ties.
 3. A railway skate car retarder as defined in claim 1, wherein said biasing means is a helical compression spring which extends said movable support and moves said brake means to said braking position.
 4. A railway skate car retarder as defined in claim 1, wherein said power gear operated locking means includes an electric motor and a worm and gear for latching and unlatching a pair of splined fittings.
 5. A railway skate car retarder as defined in claim 3, wherein said helical compression spring is internally located in a tubular piston and slide cylinder member.
 6. A railway skate car retarder as defined in claim 1, wherein said power gear operated locking means includes a motor and gears for operating a spline type of latching device.
 7. A railway skate car retarder as defined in claim 1, wherein said movable support includes a pair of telescoping members which are urged outwardly by said biasing means.
 8. A railway skate car retarder as defined in claim 2, wherein said slide cylinder is constantly urged to an extended position by said biasing means.
 9. A railway skate car retarder as defined in claim 8, wherein said biasing means is a helical spring which is located internally of said piston and said cylinder.
 10. A railway skate car retarder as defined in claim 2, wherein said cylinder includes a plurality of outwardly extending splines which engage a plurality of inwardly extending splines when the car retarder is latched in its closed braking position. 